Radiant gas burner and means for removing products of combustion



April 3 1951 E. B RADIANT GAS BURNIE MEANS FOR 2547735 REMovING PRODUCTS oF coMBusTIoN 2 Sheets-Sheet 1 Filed April 18, 1946 INVENTOR www ABY ATTORNEY f mm w. w Mmww/ April 3, 1951 E" BLAHA 2,547,735 RADIANT GAS BURNER AND MEANS FOR REMOVING PRODUCTS 0F COMBUSTION Filed April 18, 1946 v2 ShQQt'S-Shet 2.

llll /l/ NVENTOR um mfm ATTORNEY Patented Apr. 3, 1951 V1.55m.ANTI'[GAS BURNER ND MENSFQR REMovINoPRonUc'rs oF'coMBUsTIoN .Emil-Blaha, Cheltenham, Pa., Yassigner vto Selas lCorporation fof America, Philadelphia, Pa., a corporation of rPennsylvania.

Application Aprilil'S, 1946, 'Serial 'Nm-663,157

13 Claims.

My invention relates togasburners, Fand is especially concerned with burners of .this type 1in which a large 4fraction :of 'the heat-generatedand developed by combustion oi .a combustible gas mixture is converted to `radiant heat.

It has already been 'proposed to produce tradiant heat in a bodyiha'ving .an open cavitywhich is provided `with `a high temperature inner refractory lining forming =a `combustion space. A combustible `gas 'mixture is supplied-to such space in which combustion of the mixture is accomplished to heat the-innerliningto incandescence. By accomplishing a large part and preferably substantially all ofthe combustion of the mixture in the combustion space, extremely high combustion temperatures Ya-re vdeveloped for effectively heating the inner lining to ahighlyincandescent condition, thereby promoting the conversion `of a large fraction of `,the heatdeveloped and generated in the combustion :space to radiant heat which is projectedfrom'the highly incandescent inner lining fordoing useful Work.

In such gas burners the highly :heated zgases produced in the combustion space, 'and consisting largely of heated products of combustion., pass from the open end of the cavity into the environment in which jheating of work is to .be Aeiected In many instances such =highly .heated gases vmay be `eiiciently utilized for-'convection heating purposes, Aand, together with vthe radiant 'heating component, effect the desired heating of work. However, there are certainfheating applications in which the convection .heating effectedby the high temperature heating `gases fisobjeCtiOnable and undesirable. This fis especially true in the tiring of articles Ato produce glazed surfaces,ias.in the glost iring of ceramic Ware and .in vitreous enamelling, for example.

To produce `'enarnelled*articles having a vitreous or `glass-like surface nlm, a coating of'non-vitreous or `inorganic material, usuallyin'the "form of a slurry, is applied to the articles vwhich fuses when 'heated and/is converted to a vitreous or glass-like film. This molten glass-like iilmsolidiesan'd hardens when the articles to which the coating material Vis 'applied are subsequently cooled. Such `vitreous-'or glass-'like--lm, as well as the glazed surfaces `produced in the glost firing of lceramic ware, should ybe lustrous and smooth andifree of surface defects.

When highly heated gases pass from the open cavity of a radiant type burner of theabove Itype and circulate Yfreely in a heating chamber in which 'articles are "being fired to produce glazed surfaces thereon, such 'heating "gases tend :to virnl2 pair andadverselylaiiect 'the .smoothfand lustrous suriacerdesired. Thisis sobecause the high-temperature ,products .of combustion which .come linto Y contact With the articles contain harmfulimpuri--` ties, such as sulphur dioxide and sulphuricfacid fumes, -for example. In order to insure-the production of :glazed :and :glass-like surface on ..articles -Which are smooth vand lustrous and-*free :of any fsurfacedefects, it'has'been'the general. practice to employ internally -iirfed heat radiating muffles'to keep the articlesioutf of physical contact with 'the vhigh 'temperature gases consisting of heated products of combustion.

YIhave discovered .that-workcan be'red atfhigh temperatures -by radiant heat projected -from gas burners .of the above radiant :type `without the necessity :of shielding-the work orgoods vfrom the combustion zonesby a heattransier Ywallfor barrier, thereby eiecti-ng radiant heat transfer at the highest possible y'temperature from the combustion spaces or zones whose wall Surfaces are heated to a highly incandescentlcondition. lI accomplish this by supplying -the-combustiblegas mixture to the combustion space or burner cav ity in such a manner'and at such a `rate thatthe inner refractory lining thereof is maintained highlyincandescent and -asubstantial partici -the combustion of the mixture is completed in the space, and Vby twithdrawing from the Y`space the heated gases generated vtherein beforeA such gases pass from-the -open end of the -burnercav-ityinto the renvironment to which `hea-t is yradiated from the inner lining.

In those I.heating applications where any pronounced .forward movement of the heated gases from the open end Vof the burner cavity is robjectionable, Athe gases `at the region adjacent to the lopen end of the cavity `may -be maintained practically-quiescent by withdrawing anddiverting substantially all of the heated lgases developed and generated inthe combustion .spaceof the burner. In such .case the heated gases pass at a very slow Vrate and substantially by diffusion only from the .combustion space through the open end of the burner cavity to theenvironmentadjacent thereo.

When radiant'burners of the invention are incorporated'ina wall of a heating-chamber, heated gases enter the heating chamber Vfrom the .burn-` ers only by dilusion at the open ends of the burner cavities. This 'takes place at an extremely slow'rate, and, inthe .glazing of articles, the degree to which sulphur impurities'are carried "into the chamber .atmosphere is extremely small and'insuicient to impair the smooth and 3 lustrous surface produced on such articles. Hence, in employing such radiant burners for heating work or goods in a closed chamber, the chamber is filled with gases which may be referred to as poor products of combustion, that is, products of combustion which are impoverished in sulphur impurities.

An important operating characteristic of radiant burners embodying the invention is the practically quiescent condition of the gases at the region adjacent to the open end of the burner cavity. When the heated gases are withdrawn from the combustion space and diverted before such gases can pass from the burner cavity into the environment into which the radiant heating component is projected, there is no blast or current of heated gases which can be felt by the hand when it is momentarily placed in front of the burner cavity. Therefore, when radiant burners of the invention are employed in a wall of a heat chamber, the furnace atmosphere may be maintained practically quiescent and the only circulation of gas therein will be that due to any diierences in temperature in different parts of the chamber.

The heated gases generated and developed in the combustion space of the burner are preferably withdrawn therefrom at a region removed from the inlet through which the combustible gas mixture is supplied to the burner cavity. In the embodiments illustrated and described hereinafter, the heated gases are withdrawn through an outlet provided at the large open end of the burner cavity. The outlet communicates with one or more passages to which are connected a suitable exhaust blower, whereby the suction effect produced by the blower is reflected back to the outlet to maintain the latter at a pressure below the pressure prevailing in the combustion space of the burner. Thus, the heated gases are effectively diverted through such outlet instead of passing from the combustion space into the environment to which heat is radiated from the inner wall surface of the burner cavity. In order to effectively utilize the heated gases thus diverted from the burner cavity when the burner is incorporated in a wall of a heating chamber, the passages through which such gases pass may be embodied in the wall of a heat chamber. In this manner the collecting flues for the withdrawn heated gases may serve as mufiies for indirectly heating the chamber through the flue walls.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the claims. The invention, both as to organization and method, together with the objects and advantages thereof, will be better understood by reference to the following description taken in connection with the accompanying drawings of which Fig. 1 is a plan view of a front face of a gas burner embodying the invention; Fig. 2 is a sectional view, taken at line 2 2 of Fig. 3, to illustrate details of the gas burner immediately beneath the front face thereof Fig. 3 is a central sectional View, taken at line 3 3 of Fig. 2, to illustrate the gas burner more clearly and the connection thereto of an exhaust blower for withdrawing heated gases developed and generated in the burnervcavity; Fig. 4 is a fragmentary sectional view, taken at line ll-l of Fig. 3, to illustrate details of the front inner body of the gas burners for holding an apertured plate at the enlarged open end of the burner cavity; Fig. 5 is a sectional view taken at line 5-5 of Fig. 4; Fig. 6 is a perspective view of the parts forming the front inner body of the gas burner of Figs. 1 to 5 inclusive; Fig. 7 is a fragmentary longitudinal sectional view of a furnace in the side wall of which are incorporated gas burners illustrating another embodiment of the invention; Fig. 8 is a fragmentary horizontal sectional view of the burner wall of Fig. 'l to illustrate the burners and flue connections therefor more clearly; and Fig. 9 is a view diagrammatically illustrating the operating conditions that may prevail in the burner cavity.

In Figs. l to 6 inclusive is illustrated one form of gas burner in which a large fraction or proportion of the heated gases generated and developed by combustion of a combustible gas mixture is converted or translated to radiant heat. The gas burner of Figs. l to 6 comprises a molded burner block I0 of ceramic material. Although not to be limited thereto, the burner block I0 is especially suitable for mounting in a wall of a heating chamber, such as a kiln, lehr or furnace, for example. As will be readily understood, a number of burner blocks I0 may be distributed in a wall of a heating chamber in any suitable manner to produce the desired heating effect.

The burner block I0 is rectangular in crosssection and formed of a number of ceramic parts or bodies which are united together by a suitable high temperature cement. As shown, the burner block IU is formed with a central passage Il which extends therethrough and terminates at a cup-shaped space or cavity I2 provided in the ceramic body I4 at the front part of the burner block I0. Within the passage II is disposed a burner tube or sleeve I5 of refractory material having one end thereof terminating at a region closely adjacent to the end of the passage communicating with the cavity. An intermediate portion of the tube I5 is formed with an outwardly extending shoulder I6 which snugly fits against a collar I1.

The collar I1 is accurately positioned in an enlarged recess at the rear of body I4, as by cement, for example, so that the end of the tube I5 terminating at the cavity I2 is properly positioned with respect to the cavity. The portion of the tube I5 extending rearwardly from the shoulder I6 is positioned in an enlarged opening or well I8 which is in alignment with and serves as a continuation of the passage I I. To the rear end of the tube I5 is fixed, as by cement, for example, an apertured plate I9. One end of a contractible and expansible bellows 20 is secured to the apertured plate I9, the opposite end of which is secured to another apertured plate 2I.

The plate 2I is removably secured, as indicated at 22, to the spaced apart legs of a supporting bracket 23. The bracket 23, the legs of which are distributed about the bellows 20, is bolt connected at 24 to a back plate 25 which is fixed in any suitable manner (not shown) to the burner block I0. In the opposing faces of plates I9 and 2| are provided pins 26 to receive the ends of helical coil springs 21 which are arranged to exert force against the tube I5. In this way the shoulder I6 of the tube I5 will always be urged snugly against the collar I1.

A combustible gas mixture is delivered from a suitable source ofsupply through a conduit 28 threadedly connected to the aperture in plate 2|. Suitable controls (not shown) may be provided to adjust the pressure and rate at which the combustible gas mixture is supplied to the burner block it. `The 'combustible gas fmixture ipas'ses through the bellows 2|l into .the tube |5.

VThe end of the tube |5fa'djacent vto the cavity I2 is internally threaded to receivean .exteriorly threaded part of an-orice member or .burner tip.

29 formed of -refractorymateriaL The gas mixture in the tube l is subdivided into va plurality of gas streams by a .plurality of slots or channels Sii formed about the periphery Vof .and eX- tending lengthwise of the narrow part .of vthe orifice member 29. The ends of the channels .30 at the rear of the enlarged end of theorice member 29 flare outwardly toward Lthe inner wallsur face 3| of the cavity |.2.

The gas mixture is discharged .from the out'- let ends 32 Yof .the channels .and it vis at theseregions that the burner .flames are Vproduced .and maintained. The 4individualflames produced at the outlets 32 of the channels 30 flare outwardly and project into the .cavity 2 alongside of the outwardly flaring wall .surface .3|. The gas flames maintained at the slot outlets 32 effect such .heating of the inner wall surface 3| that the latter is heated to incandescence. The gas mixture then introduced .into the cavity |2 is subjected to intense radiant heat of .the inner wall surface 3| so that substantially .complete burning of the gas 'mixture may be accomplished in the cavity before the heated gases pass from the open end of the cavity.

By accomplishing a large vpart and preferably substantially all of the combustion of `the gas mixture in the combustion space formed by the cavity l2, extremely high combustion temperatures are developed to heat the inner wall surface or lining 3| to a highly incandescent condition. In this manner 'a large proportion of the heat developed and generated in the combustion space is converted or translated to radiant heat which is projected from the highly incandescent wall surface for doing useful work. K

In accordance with the invention the highly heated gases generated in the cavity I2 and consisting primarily of heated products of combustion are withdrawn therefrom before such gases can freely pass from the open end of the cavity into the environment 'to which radiant heat is projected from the inner wall surface 3|. I accomplish this by positioning at the open end of the cavity l2 a plate 33 .having an opening 34 therein of approximately the same size as. the cavity opening. The plate 33 is spaced a short distance from a lip 35 provideda't the front face of the body i4 about the cavity opening to form a gap 35 therebetween.

The gap 33 serves as an outlet for the combusticn space or cavity E2 land through which the heated gases are withdrawn and diverted before passing outwardly through the open end of the cavity. The diverted gases pass through the gap 33 into an annular-shaped manifold chamber 3l formed at the front face of the burner blccl; t and thence iiow through tubes 38 which extend rearwardly from the manifold through the burner block to they back plate 25. The rear ends of the tubes 38 -are connected by conduits 39 to a main conduit 40 to which is connected the inlet cf an exhaust blower lla which may be driven in any suitable manner, as by anelectric motor, for example.

The plate 33 is positioned'relatively close to the forward edge of the lip 35 defining the vopen end of the cavity l2, so that a restricted 'outlet is provided by the `gap 36 at which region .'the suction effect produced bythe exhaust .blower LSI , the front face of 4ta-.is intensied in "a .mannersimilarfto eth'efsuction effect produced y'at -lthe :nozzle .of .fa 'vacuum cleaner.. Since `.the :burner .block t0 .is .subjected to elevated temperatures as high as 2'600" Lto 2800 :F. at .the :inner .face thereof.. especially When'incorpor'ated in a refractory'wallbf a .heating chamber, the plate 33 .must .not only withstand- .thermal 'shock ibut for Aholding .such .I plate accurately .in position 11n der :all .of the operating conditions encountered.

To this `end .the inner vfront Vbody |15 lof .the burner block l| 0 is .constructed linsuch ra manner .1.igidly-held-.partof the body. As shownlmost rclearlyin Eig.. .6, :the body I4 comprises a refractory shape .M having fslots orchannels 142 'extending lengthwise of theshape at the cuteaway corners thereof. The .slots for channels F42 are more or lesslugshaped in :crosssection .and 'formed with outwardly flaring :side Walls .toireceive ti'errods 43 .havin'genlarged end portions44.. .Thes'lots .42 :are 'deeper .at ithetfront and rear .lends than .Iat `.the intermediate .portions,.as shown in .Figs 15 yand 6, .to .receive'the enlarged ends -44 of the tiero'ds 43.

The tie rods-43, which are .more or less .trian- `gular-shaped .in .section-'are firmly secured .in

position in .the 'slots v4r, .as by cement, for example. When the vtie .rods 'are 4.secured in 'position, the refractory shape 4| and the tie rods embodied therein form the 'rectangular-shaped body Minavingsmooth outersurfaces at the four side Walls thereof to facilitate .mounting `such body 'in the vburner fblock I0.

V.'lihe enlarged forward iends '44 of .theti'e rods 43 .are notched lat the inner :faces thereof, as .indicated 'at 115, to receive Vthe cut-away corners of Lthe apertured plate 33. The 'notches 35 faccurately Vposition :the .plate v33 'a from .the lip 'or 'raised portion 35 at 'the front face of the .refractory shape 4|, the plate33 .being secured Sin position Vin any suitable manner, as by cement.

.After "the body burner `block 1w,

r4 'is fixed lin position in the la refractory part .4s forming theiburner is secured in iplace. The refractory :par-t :46 fis "provided with `a centrai i opening `which is slightly larger 'than "the opening 3'4 .in the l.plate 33, land 'the .edge portion of `such l.part ab'out the opening :is `'adapted to bear against the rplatef.

The sides `of the refractory part 43 are more or less L-shaped!insection,.as best shown inFig. 3, and the :flange vor wall `.portion 41 thereof .extending `rearwardly `from `the i'fr'ont face yof the burner block It) .is fise'cured .in position, as by cement, in a recessed "portion formed about the periphery of .an outer refractory 'wall 'part V138. The refractory `parts 46 and 48 :arelformed to provide the enlarged manifold chamber 31 which extends about the entire .'fron't face of the burner block IU and .into which the iheated gases pass through Vthe gap 36 from the Acombustion space or cavity SI2, vvas .previously explained.

.In Figs. 7 and 8 .is illustrated anotherembodiment of the vinvention for incorpora-ting a number of similar gas burners ma in a side Wall 5|) ofaa heating chamber 5| having iiue passages 52 therein communicating with lthe burners. The furnace providing the heating chamber I5| includes ythe spaced vapart side walls 53, one of which .isshown in Fig. '7, a connecting `roof 53 and `'a .oor V54. 'Thegoods `or workto be heated may be carried on a car which `is adapted to travel `on the fioor 54 'through an end 55 of the furnace. The rloading .platform of the car provision must .be made fixed .distance is preferably of such height that the goods or work to be fired or heated will be at a level directly opposite the burners Illa in the side walls 50.

The burners Illa are in spaced apart relation in the side walls 56 and arranged in vertical rows, as shown in Fig. 7. Each gas burner IIla comprises a body I4 of refractory material in which are embodied tie rods 44 and a front plate 33 similar to that shown in Figs. 2 to 6 inclusive and just described. The combustible gas mixture is supplied to the cavities I2 of the burners Illa in a manner generally like that shown in Fig. 3, similar parts being referred to by the same reference numerals.

In Figs. 7 and 8 the blocks or bodies I4 are mounted at the inner face of the side wall D between vertical rows of refractory blocks 56 which do not extend into the chamber 5I as far as the refractory bodies I4. Refractory plates 46a are arranged between adjacent vertical rows of burners Illa, the outer vertical edge portions of which bear against the plates 33 fixed to the refractory shapes 4I. The refractory plates 46a correspond to the plates 46 in the gas burner flrst described and cooperate with the refractory blocks 56 to form vertically extending spaces between adjacent vertical rows of burners Illa.

The refractory plates 46a are T-shaped in section, as shown in Fig. 8, and the blocks 56 are formed with relatively deep slots to receive the rearwardly extending legs 41a of such plates. ln this manner the vertical spaces in front of the blocks 56 are divided into two manifolds or flues 52 each of which communicates with the gaps 36 in each vertical row of burners Illa, the heated gases generated and developed in the cavities I2 thereof can be withdrawn through the gaps 36 into the manifolds or flues 52 provided at both sides of the burners.

The T-shaped refractory plates 46a are provided directly one above the other to form the flues 52 which are coextensive in height with the vertical rows of burners Illa. The upper ends of the flues 52 are closed and the lower ends thereof communicate with a larger. horizontal flue 5l provided at the bottom part of the side wall 56. The horizontal flue 51 extends longitudinally of the furnace and is connected by suitable conduit connections to an exhaust blower (not shown) in a manner generally similar to the connection of the exhaust blower 4Ia to the burner block I6 first described.

The principles of the present invention have been shown and described above in connection with gas burners of the radiant type like that disclosed in Hess Patent No. 2,215,079, granted on September 17, 1940, in which a large proportion of the heat generated by combustion of a combustible gas mixture in a combustion space or burner cavity is converted to radiant heat. In burners of this type the orifice member 29 is so positioned at the end of the tube I5 that the inner cones of the individual flames will always be out of contact with the cavity wall surface irrespective of the lengths of the flame. This is indicated more or less diagrammatically in Fig. 9 in which the inner cones of different size flames A', A2 and A3 always extend more or less along an axis B alongside of the inner Wall surface 3 I.

The relationship of the angle of divergence of the individual flames and the shape of the wall one vertical row of burners Ia. Thus, for

surface 3I of the combustion space or cavity I2 is fully disclosed in the aforementioned Hess patent which may be considered as being incorporated in this application, and, if desired, reference may be had thereto for a more detailed description of the burner structure.

In accord with the present invention the suction effect produced by the exhaust blower is reflected back to the restricted outlet or gap 36 provided at the open end of the combustion chamber or cavity I2. The suction effect is intensied at the gap 36 and the pressure at this region is below and negative with respect to the pressure prevailing in the cavity I2. By providing any well known control provisions for controlling and regulating the suction pressure produced at the gap 36, such as a damper 58 in the conduit 40, substantially all or any desired fraction of the heated gases generated in the burner cavity I2 can be effectively withdrawn from the cavity and diverted through the gap 36, as indicated by the arrows F in Fig. 9, before such heated gases can pass from the combustion space through the open end of the cavity I2 into the environment into which heat is radiated from the wall surface 3I.

The suction pressure produced at the gaps 36 of the burners I and Illa is related to the pressure at which the gas mixture is supplied to the burners and the lengths of the individual flames produced in the cavities I2. When the burners are being operated at low capacity and the flames are relatively small, the suction pressure produced at the gaps 36 is correspondingly adjusted so as to avoid pulling the flames from the Wall surfaces 3l and reducing the effectiveness of the flames in heating the cavity lining to a high incandescent temperature. This is so because the flames produced in the burner cavities are what may be referred to as lazy flames when the burners are being operated considerably below maximum capacity. When the pressure at which the gas mixture is supplied to the burners is increased, the suction pressure produced at the gaps 36 may be also increased.

In gas burners of the type illustrated, there is a tendency for the individual flames to bend inwardly toward the axes of the burners in a manner akin to the bending of the ribs of an umbrella when it is fully opened. It has been found that the suction effect produced at the gap 36, which completely encircles the open end of the cavity I2, tends to overcome such lifting of the individual flames from the cup surface 3i and promote a more uniform incandescent heating of the wall surface. Hence the suction pressure produced at the gap 36 can be effectively controlled and nicely regulated to cause the flames, which vary in length depending upon the gas mixture delivery pressure, to remain closely adjacent to the wall surface 3| of the cavity and promote effective radiant heating of the cavity lining.

It has been observed that when a gas burner is being operated at less than maximum capacity, the area of the wall surface 3| of the cavity heated to incandescence is increased when radiant burners of the type described herein are provided with restricted outlets at the open end of the cavity at which a suction pressure may be produced. Thus, by maintaining the suction pressure at the gap 36, the radiant heat is at the same thermal head as heretofore but is distributed over a wider area of the cavity wall surface.

particularly.- wh-en thefburnenis; operated at: less than` maximum capacity The gasmixture suppliedtotheburners Hl, and lila may be a, complete mixture in Whichi all of the combustion sumiortingl gas; such: as air, for example, is supplied with the combustiblegas to effect complete burning or combustion of, thelatter in the'l cup-shaped cavity l2. Under these conditions, thesuction pressure produced: at the gap 36 may begregulatedjto` withdraw and'divert throughthe gap substantially all` of the heated gases generated andA developed in the, burner cavity, so as to. maintain theJ regionat the open end of the cavity |Zpracticallyquiescent When such operationof the gas burner isyeffected, no blast oi. heated gases.. can be felt-by the hand when it is momentarily placed over the open` end of the burner cavity. The lsuction;` pressure; pro,- duced at the gap can thereforebe regulated t maintain the gases immediately irrfront of the open,l cavity practically` quiescent,` so that the heated, gases can pass substant-ially by diffusion onlyY from the cavity into the environment'immediately.' adj acent,` to f theV open, endy ther,eofj.

The; suction pressure produced at; the:,gap3 may be valso regulatedtorminimize the-ficwof the heated gases by diifusion from` the open end of the cavity. This-f may be; accomplished by: producinga suction-pressu-reqbelow the pressure prevailing in; the cavity i2,- and; the regicnadjacent to: the open end; thereof which; is.,y 0f Such; meer nitude-as to produce asubstantialiiniiowcf the gases; into the open ende ofV the-cavi-tv;j,asaindr cated by,A thev arrows C in; Fig.Av 9.,v Such gases drawn into the open-end of,v the-,cavity I 2; pass, toward theg gap 3,6. and; flow therethrough. along with the heated; gases; diverted froml the cavity. It isftoA beundersto'od that there willalwaysbe a tendencyfor gases to be;A drawn into, the open end of the cavity l2 due to the-suctifmA pressure produced at thegap 36'; When-v acompletr-f` gas mixture is supplied tothe-fburners,l the suction pressure is preferably properly related tothe-gas mixture delivery pressureY to effect-substantially complete combustion off such, mixture in the burner cav-ity.`

When burners of the invention are employed to heat an enclosed space` like the. burners; a in Figs. 7. and,l the gas mixture.y suppliedito, the

burners may be a partial mixture and some of the. air to accomplish complete burning of the combustible gasmay be drawn into the burnercavity by the negative pressureproduced at. the gap 3B. The admission. of air into. heating chamber 5|` may be: due to leaks inthe walls of the1 chamber., Such air passing into the heating chamber. is heated therein and, due to such preheating,V is capable of producing higher combustion ,temperatures in the burners when drawn into the cavitiesl thereof; Inward movement of heated air into a burner cavity I2 may be promoted due to the pressure conditions prevailing in the'cavity. There* is a low pressure region at the center of the cavity 22 adjacent to the enlarged end of the tip or orifice memberv 29, into which gases tend to be drawn, as indicated bythe arrows D inA Fig. 9.= SinceV the suction effect produced-'at the gap'36 is strongest at therinr of the cavity andlweakst at the central region thereof, an adequate w of heated' air` may be induced at the` center ofr the cavity, as indicated bythelarrowsflii in Fig. 9; to supplyl part of` the' combustion supporting gas for effecting combustion of the combustiblefgas suppliedin a partialfmixture to the-'cavity |21.

positively controlled or may Gas-f. burners embodying-z the: invention are especially. usefulV in; the firingof glazed surfaces, aszin, the, glost firing of ceramicV ware andl in vitreousjenamelling, for example; In such heat-.- ing applications the work can be red at high temperaturesI by radiant heat projected directly from;thewall surfaces-3| of the cavities l2, withoutthe, necessity ofshielding the work by a heat transfer wall, so that radiant heat transfer can be eiected at theA highest possible temperature from the burner cavities whose wall surfaces are heated to a highly radiant condition.

` When` the heating chamber 5| is employed for firing articles toproduce glazed-,surfaces thereon the furnace is first brought up. to the desired temperature., by theburners Ia. If no provision were made for diverting the heated gases generated through the gaps 36. and the heated gases could freely pass into theV heating chamber 5|, the, impuritiesv in such gases, such as sulphur dioxide andv Sulphuric acid fumes, for example, Would adversely affect the glazed orglass-dike surfaces produced on articles being red. However, in operating the burners lila, heated gases can pass by diffusion only from each burner cavity I2, into thechamber 5I.

Since the rate at 'which the heated gases pass into` the chamber atmosphere by diffusion is relatively low,l the extent. to which objectionable impurities,are carried into the-gas present in the chamber` is; extremely small and insuflicient to adversely affect the smooth and lustrous glazed surfaces produced on work. The heating chamber; 5|, is desirably'c-losed after the work or goods to;` be fired is` positioned therein for producing glazedsurfaces on the work: Under these conditions the chamber 5| is filled with gases which arefimprover-ished in impurities and usually referredtoasfpoor products of combustion.

When burners of. the invention are incorporated in a wall` of a heating chamber which is substantiallyclosed, as the heating chamber 5| of Fig. 7, for example, the pressure in the chamf ber is below atmospheric pressure and negative dueto thev suction pressure produced at the gaps 3,6.1of the; burners lila. Hence, the pressure in a closed heating space red with burners l ila will belessthan thepressure in the usual furnace` or heater -in'which the gaseous atmosphere is posi- `tive and above'atmospheric pressure. rlhe fact that `a heating space ory chamber is at a negative pressure when red by burners of the invention is not; objectionable, unlessl there is excessive leakage of airY in the chamber, asv through cracks in thev walls thereof, for example. An excessive amountof air in the heating chamber exercises a cooling eifect and tends to reduce the temperature of the wall surfaces 3| of the burner cavities I2.

`When an excessive amount of air enters the heating-f chamber the adverse eect. of such air ati. the. burner cavities can be overcome by increasing the. suctionv pressure,r produced at the gaps 36. However, it is desirable to eliminate the leakageV of air into the heating chamber when the presence. of an excessive amount of air in the Chamber interferes with the operation of the burners;. especially when it is desired to operate theaburners to.` provide radiant heat at theA highest possible temperature to. producea high thermal head for heating `Work in a minimum length of time..

When work is' being fired in a closed heating space, such as the heating chamber 5|., to produce glazed.' or.y glassflike surfaces on work,the

atmosphere in the chamber is desirably oxidizing. In such case air admitted into the heating chamber may be referred to as essential air in that it purges the gases in the heating chamber and contributes to the production of high quality glazed surfaces on the work. However, any air passing into the heating chamber over and above Vthat necessary to effect the desired end result may be referred to as unessential air, because such air causes an undesirable drop in temperature in the heating chamber and does not serve any useful purpose.

In the operation of the heating chamber 5I of Fig. '7, -when the latter is completely closed at both ends thereof, whatever circulation of gas takes place therein is due solely to leakage of air through the walls thereof. In a properly constructed heating chamber, a more or less stagnant atmosphere is maintained in the heating space during operation of the burners ma, and any possible slight movement of the gases will occur only by reason of difference in temperatures in different parts of the heating space.

The manifold 31 for the gas burner I6 and the vertical flues 52 for the burners Illa are preferably of such size that the paths of iiow provided for the diverted heated gases will be adequate to withdraw practically all of such heated gases generated and developed in the burner cavities when the burners are being operated at maximum capacity. Further, the flues 52 are considerably larger in cross-section than the gaps 36 so that the heated gases will pass at a lower velocity through the ues and give up heat to the side Walls `'.ill in which they are incorporated and also to the chamber 52 through the ue walls formed by the plates 46a.

In the event any unburned gases are withdrawn and diverted from the cavities I2 through the gaps 36 into the flues 52, combustion of such gases may be completed in the flues because the cover plates `46a become heated to an incandescent temperature which is above the ignition temperature of the combustible gas. Under such conditions the flues 52 serve as heat radiating muiiles and contribute to the heating of work in heating chamber 5I.

When a combustible gas mixture of ordinary city gas and air is supplied to the burners Ia,

such gas having a rating of about 550 B. t. u. f#

per cubic foot, the wall surfaces of the `cavities I2 may be heated to temperatures as high as 2800 F. and higher and are at a high thermal head for heating work in the chamber I. The cover plates 33 for the burners are also heated to a high incandescent temperature which may be in the neighborhood of about 2500 F. and at a thermal head slightly below the wall surfaces 3| of the burner cavities. The plates 46a for the flues 52 are also heated to incandescence and are at a lower thermal head which may be in the neighborhood from about 50 to 100F. and higher than the temperature of the gases in the heating chamber 5 I.

In view of the high temperature produced at the cover plates 33, such cover plates and the tie rods 43 are preferably formed of a refractory material, such as silicon carbide, for example, which is capable of holding up under extremely high temperatures without developing cracks and also possesses high tensile strength and resistance to thermal shock. The refractory plates 46 for the burner I and the refractory plates 46a for the ues 52 may be also formed of refractory material consisting entirely or predrawn heated gases in ponderantly of silicon carbide. Since heat transfer is effected from the flues 52 through the cover plates 46a to the gases in the chamber 5I, it is desirable to provide cover plates 46a formed of refractory material possessing good thermal conductive properties, such as silicon carbide, for example.

The refractory body I4 for the burners I0 and lila may be formed of mullite or any other suitable refractory material having poor thermal conductive properties, so that the wall surface 3! of the lcavity I2 formed at the front face of each body I4 can be effectively heated to the highest possible temperature.A The tie rods 43 effectively hold each refractory body I4 together when the inner face thereof is heated to a highly radiant condition and stresses are induced in the body due to the rear parts remaining relatively cool while the regions adjacent to and at the inner surfaces 3I are heated to high temperatures.

In view of the foregoing, it will now be understood that an improved gas burner has been provided for heating work to high temperatures by radiant heat projected from refractory wall surfaces heated to a highly incandescent condition by combustion of a combustible gas mixture. The gas burner provided embodies the refractory shape or body I4 having tie rods 43 which not only serve to increase the life of such shape but also maintain the apertured plate 33 accurately positioned a short distance from the raised lip 35. rI'he tie rods 43 of high tensile strength tend to retard cracks developing in the refractory shape I4 and also tend to retard the growth of cracks after they once occur. Further, when the refractory shapes I4 rare subjected to repeated thermal shock over a long interval of time and such shapes may split, the tie rods 43 effectively hold each body together and prevent any part thereof being dislodged.

While the exhaust blower 4Ia has been provided to produce a suction pressure at the gap 36 of the burner I0 in Fig. 3, it will be understood that such suction pressure may be produced at the burner I and also the burners Ia in Figs. 7 and 8 in any other well known manner, such as, for example, by a steam or air ejector. Moreover, if it is desired to avoid the necessity of employing a high temperature exhaust blower, air may be drawn into the inlet of the exhaust blower along with the withdrawn heated gases to reduce the temperature of the latter. In addition, a heat exchanger may be connected in the conduit 4e to bring the withheat exchange relation with another fluid to which heat is given up by the heated gases.

lIn the embodiments of the invention shown and described, the size of the aperture 34 in the plate 33 of each burner is suitably related to the opening of the cavity I2 at the rim 35, so that the heated gases will be effectively withdrawn from the cavity when a suction pressure is produced at the gap 36. This is accomplished in the embodiments of Figs. 1 to 6 and Figs 7 and 8 by providing apertures 34 in the plates 33 which are slightly less in diameter than the extreme open ends of the burner cavities.

Attention is called to applicants copending application Serial No. 663,158 filed concurrently herewith, now Patent No. 2,509,856, which is directed to the structure of a kiln or furnace wall. Attention is also called to applicants copending application Serial No. 663,159 filed conarranges currently herewith, now: Patent No.. 2,474,301', which ist, directed to a method of firing; a kiln..

Although I haveshown anddescribedf: several embodiments of the invention, it will. be. obvious to thoser'skilledin the artV that modificationsv and changes mayV beI madexwithout departingv from the spirit and scope offtheinvention.` Thus, the principlesaof the invention maybe app-liedfequally Well to other forms-of gas burners than that disclosedherein in which a .large fraction or proportion of." the heated. gases generated and'developed by the.` combustion of` a combustible gas mixture is converted: or translated to radiant heat.. I therefore aim in the following claims. toY cover all modications: and.' changes which fall 'within theftrue spirit and scope ofthe invention.

What is.l claimed is:

1. A1 gas burner comprising flame distributing meansfor spreading a burning `gaseous mixture including a. combustible gasA and. a combustion supporting. gas, structure including a member having a high temperature .cup-shapedl'refractory surface; theV distributed flame produced by` said distributing: means extending alongside saidl surface', said distributed amebeing effective to heat saidsurface tozincandescence; said' member cooperating withY said.'distributingmeans-so that substantially the only combustion supporting gas passing through said member to the region at which the distributed flame isV` produced is that supplied by said distrilmtingmeans, and said structure providing an outletr surrounding the edgeofisaid cup-shaped surfaceand-1 communieating therewithv and extending outward1yina radial direction therefrom', and means through whichy a pressure whichV is negativev with respect tothe pressure at the region the distributed flame is maintained and through which is dischargedand diverted a large fraction of the heated gases generated' at vsaid region insteadfof flowing therefrom into the environment/to which heat isrradiated-from said` surface.

2. A gas burner comprising structure including a. body having an open cavity at a face thereof, saidcavityl being providedwith aV high` temperature inner refractory wall surface forming a combustion space having an apertured inlet member forv subdividing into a pluralityof" gas streams. a fuel mixture supplied thereto which may burn within said spaceto heat said inner wall-surfaceA to incandescence and'produce-a regionof intense heat in which a large fraction of' thecombustionis completed, and said structurev providing aradially extending outlet` axially aligned in frontfcf-said cavity and communicating therewith andl surrounding the same, and means through which said outletisf` maintained ata pressurewhich isnegative 'with 'respect to theipressure in said space andthroughwhich is discharged .and divertedja large fraction of'the heated gases generated, in said space instead of flowing outwardly therefrominto the environment to, which heat isradiatedfrom saidinner wall surface.

3. Agas burner comprisingstructure. including a body ofhigh temperature refractory havingan open cavity at aA face thereof providedwithan inlet, member` formed ,with a series` of flameV projecting orifices, said cavity having a. wall surface alongside of which the llames projected from said aricesextend, the flames beingeffective to heat. said inner Iwall surface toY incandescence, and. said sti-tucture.providingan outlet for said cavity encircling: the,` edge thereof at aregion removed: from. said oriiices andv communicating therewithn and extending: radially outward therefrom7 passage.L means: communicating with the outlet, andmeans embodied inthe passage means for,A producing. a; suction. effect at theoutlet: to maintain the latteratga pressure below the prese sure: prevailing. in` said.v cavity to divert through thefoutl'et into said: passagemeans a larger frac.- ti'on of the heated gases; generated in Ysaid. cavity instead of flowing outwardly therefrom into the environmentto which heat is radiated from said innerfwall surface.

4. A, gas; burner comprising flame distributing means, structure including a cup-shaped member havinga, high temperature refractory surface alongside ofy which the distributed flame produced byzsaid distributing means: extends,` said distrib; uted; flame being eifective: to heat said surface to` incandescence, said structure providing an outelt. associated'. with said member entirely around. thef edge of said surface at a region removed from saiddistributing means: and com.- municating therewith and extending radially outward therefrompassage means communicating. with theouztlet, and means embodied in said passage means for producing a suction eifect' at the outlet; to maintain the latter at a pressure below thef pressure prevailing at. the region the distributedv flame is'produced; to divert through the outlet into: said passage means a. large' fractionfof theheatedzgases generated atsaid region instead` of flowing therefrom.. into the environmentito which heat is radiated fromsaidxsurface;

5.; mgas burner comprisingfame distributing means, structureA including. a member; having a high;l temperature refractory surface alongside ofwhioh. the distributed il'ame produced by said distributing. means .extendssaid distributediiame being. effective to heatsaid surface to incandescence, said structure providing at a region` removedY frome said distributing means: an. outlet enti-relyY surrounding. the edge of said member and. communicating therewith and extending radiallyl outwardl therefrom, passage means com:- municatingwith the outlet, and means including an exhaust blower connetced in said passage means; for producing a suction effect at the outlet to maintain the latter at a pressure below the. pressure-.prevailing at the region the distributed dame is produced to divert through the outlet intosaid passage meansv a large fraction off the heated; gases generated at said region instead. of: flowingtherefrom into the environment vto which heatis radiated from said surface.

6,. AA gas' burnerv comprising: structure including a; body of refractory material havingV an open cavity-at a face thereof, said'. cavity having an innerrwail surface forming a combustion space providedfwith aninlet through which a fuel mixture supplied; under -pressureamay be burned within said: space tof heat the inner surface to incandescence,l said structure including a member of refractorymaterial having an opening: therein said memberfbeingpositioned at said face with said, openingv in front. of.` said cavity, aligned therewith and spaced therefrom to provide a radiallyV extendingy gap. between said face and member, and means to maintain said gap at a pressure whichl is negative 'with respect to the pressure insaid space and through which heated gasesgenerated insaidspace may be discharged and diverted: instead of: flowing outwardly therefrornlintog'the environment to which heat is radiated from I the inner` surface through the. opening in. said chamber.

7. A gas burner comprising structure including a body of refractory material having an open cavity at a face thereof, said cavity having an inner wall surface forming a combustion space provided with an inlet through which a fuel miX- ture supplied under pressure may be burned within said space to heat said `surface to incandescence, said structure including a plate of refractory material having an opening therein, said plate being positioned over the open end of said cavity with said opening aligned with said cavity and said plate spaced from said face to provide a gap therebetween which is removed from the inlet, passage means communicating with the gap, and means operatively associated with said passage means for producing a suction effect at the gap to maintain the latter at a pressure below the pressure prevailing in said space to divert through the gap into said passage means heated gases generated in said space instead of flowing outwardly therefrom into the environment to which heat is radiated from the inner surface through the opening in said plate.

8. A gas burner comprising structure including a refractory shape having an open cavity at a face thereof, said cavity having an inner wall surface forming a combustion space provided Iwith an inlet through which a mixture of a combustible gas and a combustion supporting gas supplied under pressure may produce combustion in said space which heats the surface to incandescence, means embodied in the shape to hold the latter together when the inner surface of Said cavity is heated to a highly radiant condition and stresses are induced in said shape due to uneven heating thereof at regions adjacent to and removed from the inner surface, said structure including a plate of refractory material having an opening therein, and means including said shape holding means for locating said plate over the open end of said cavity with the opening therein aligned with said cavity and said plate spaced from said face to provide a gap therebetween which may be maintained at a pressure below the pressure prevailing in said space and through which may be discharged and diverted the heated gases generated in said space instead of flowing outwardly therefrom into the environment to which heat is radiated from the inner surface through the opening in said plate.

9. A gas burner comprising structure including a refractory shape having an open cavity at a face thereof, said cavity having an inner wall surface forming a combustion space provided with an inlet through which a mixture of a combustible gas and a combustion supporting gas supplied under pressure may produce combustion within said space which heats the surface to incandescence, means embodied in said shape for holding the latter together when the inner surface of said cavity is heated to a highly radiant condition and stresses are induced in the shape due to uneven heating thereof at regions adjacent to and removed from the inner surface, said holding means comprising tie rods of refractory material of greater tensile strength than the material forming said shape for anchoring regions of the latter adjacent to and removed from the inner surface, said structure including a member of refractory material having an opening therein which is positioned over the open end of the cavity with said opening aligned with said cavity, and means including said shape holding means for positioning said member in spacedrelation to said face to provide a gap therebetween which may be maintained at a pressure below the pressure prevailing in said space and through which may be discharged and diverted heated gases generated in said space instead of flowing outwardly therefrom into the environment to which heat is radiated from the inner surface through the opening in said member.

l0. A gas burner comprising structure including a refractory shape having an open cavity at a face thereof, said cavity having an inner wall surface forming a combustion space provided with an inlet through which a mixture of a combustible gas and a combustion supporting gas supplied under pressure may produce combustion within said space which heats the inner surface to incandescence, means embodied in said shape for holding the latter together when the inner surface of said cavity is heated to a highly radiant condition and stresses are induced in the shape due to uneven heating thereof at regions adjacent to and removed from the inner surface, said structure including a plate of refractory material having an opening therein disposed over the open end of the cavity with said opening aligned with said cavity, means including said shape holding means for positioning said plate in spaced relation with said face to provide a gap therebetween, pressure means communicating with the gap, and means associated with said passage means for producing a suction effect at the gap to maintain the latter at a pressure below the pressure prevailing in said space to divert through the gap heated gases generated in said space instead of flowingv outwardly therefrom into the environment to which heat is radiated from the inner surface through the opening in said plate.

1l. A gas burner comprising structure including a refractory shape including an open cavity at a face thereof, said shape having a projecting rim at said face defining the extreme open end of the cavity whose inner wall surface forms a combustion space provided with an inlet through which a mixture of a combustible gas and a combustion supporting gas supplied under pressure may produce combustion within said space which heats the inner surface to incandescence, and said structure including a substantially flat plate of refractory material having an opening therein positioned over the open end of the cavity with said opening aligned with said cavity, the edge portion of said plate about the opening therein overlying said rim and being spaced therefrom to provide a narrow gap therebetween which may be maintained at a pressure below the pressure prevailing in said space and through which may be diverted heated gases generated in said space instead of flowing outwardly therefrom into the environment to which heat is radiated from the inner surface through the opening in said plate.

12. A gas burner comprising structure including a refractory shape having an open cavity at a face thereof, said cavity having an inner wall surface forming a combustion space provided with an inlet through which a mixture of a combustile gas and a combustion supporting gas supplied under pressure may produce combustion within said space which heats the inner surface to incandescence, a rst member of refractory material having an opening therein which is positioned at said face with said opening aligned Iwith said cavity and spaced therefrom to provide a gap therebetween, and a second refractory member overlying said first refractory member and cooperating with said shape to form a chamber communicating with said space in which a from the inner surface through the openingin said rst refractory member.

13. A gas burner comprising structure including a refractory shape having an open cavity at a face thereof, said cavity having an inner wall surface forming a combustion space provided with an inlet through which a mixture of a combustible gas and a combustion supporting gas supplied under pressure mayV produce combustion Within said space which heats the inner surface to incandescence, a plate of refractory material having an opening therein 'which is positioned at said face with said opening aligned with said cavity and spaced therefrom to provide a gap therebetween, and a member of refractory material overlying said plate and cooperating with said shape to form a chamber communicating with said space, pasasge means communicating with said chamber, and means operatively associated with said passage means for producing a 18 suction effect at said gap to maintain the latter at a pressure below the pressure prevailing in said space and divert through said gap into said chamber heated gases generated in said space instead of flowing outwardly therefrom into the environment to which heat is radiated from the inner surface through the opening in said plate.

EMIL BLAHA.

REFERENCES CITED The following references are of record in the @le of this patent:

UNITED STATES PATENTS 

